Japanese Patent Application Laid-open No. 2006-103301 discloses a chain saw that is a type of power tool. According to the disclosure, the chain saw comprises a retaining assembly that is a type of a rotation knob rotatably arranged on a chain saw body. The rotation knob comprises a knob body and a tab attached to the knob body. The tab is arranged on the knob body so as to be capable of swinging between a storing position and an operating position. When the tab is at the operating position, the tab stands upright perpendicular to the knob body. An operator can hold the tab and rotatably operate the rotation knob by moving the tab from the storing position to the operating position. The tab is biased from the operating position toward the storing position by a torsion spring. In this configuration, when the operator releases a finger from the tab, the tab swings from the operating position to the storing position due to a biasing force of the torsion spring.